Serial bus standards specify requirements for compliant connectors. For example, the Universal Serial Bus (USB) standard requires an interface (the portion of the connector that connects with a mating USB compliant connector) with four conductors and a shell. The USB standard also specifies that the four conductors carry signals that are serial digital communications. The serial digital communications are susceptible to signal integrity issues such as noise, cross talk, degradation due to impedances, or the like. To ensure that the signal integrity issues are minimized, the USB standard also requires that the conductors in the interface meet specified dimensions. However, from the interface to, for example, a circuit board, manufacturers can bend the conductors to meet non-standard specifications (e.g., customer's circuit board layout, chassis design, etc.) as long as the signal integrity requirements in the serial bus standards are met.
To meet the signal integrity requirements, the manufacturers typically bend the conductors in a planar curve to interface with the circuit board. The spacing may vary between the conductors along the lengths of the conductors. For example, in a portion along the conductors that is exposed, the spacing might be wider than the portion that is surrounded by a polymer (e.g., PTFE) insulator. Also, the distances along the surface of the insulator between the conductors, and the conductors and the shell, can vary. These issues can be problematic with respect to safety considerations, such as clearance or creepage distance.
Creepage distance is defined as the distance along the surface of the insulator between each of the conductors. Creepage distance is a concern because creepage distance can be the distance at which a discharge occurs between conductors for a given voltage. Discharges between conductors are undesirable due to safety issues. Although designers of circuit boards regularly specify creepage distance in board layouts, the distance between conductors in standardized serial bus connectors are typically specified to ensure signal integrity. That is, the standardized serial bus connectors are designed to maximize data transmission rates while meeting basic safety standards. As a result, the standard serial bus connectors are not well suited for enhanced safety standards (e.g., IEC 60079-7 (Increased Safety)) that are required in many industrial applications.
FIGS. 1 and 2 show an exemplary standard serial bus connector 10. As shown in FIG. 1, the standard serial bus connector 10 is a USB-A connector that includes conductors 12 that are disposed inside a shell 14. The conductors 12 extending from the standard serial bus connector 10 are arranged in a parallel configuration. Due to the parallel configuration, the smallest creepage distance is between the conductors 12 and the shell 14. As a result, if a discharge occurs, it will likely occur between the conductors 12 and the shell 14. The pin-to-pin spacing in the parallel configuration also does not meet spacing requirements of the enhanced safety standard. Furthermore, when mounted to a PCB, the spacing is further reduced by the PCB annular rings necessary for soldering. FIG. 2 shows an exploded view of the standard serial bus connector 10 that includes an insulating body 16. As can be seen, the spacing between the conductors 12 vary along the lengths of the conductors 12. The conductors 12 are more likely to discharge at the minimum spacing or clearance between the exposed portions of the conductors 12. The minimum creepage distance and clearance are less than those required by the enhanced safety standard. As a result, the spacing between the conductors 12, as well as between the conductors 12 and the shell 14, do not meet the enhanced safety standard requirements.
Designing proprietary connectors that meet the enhanced safety standard requirements is prohibitively expensive. For example, the proprietary design does not just require a new connector design but also corresponding inventory buildup of cables, connectors, or the like, that are able to interface with the proprietary connector. Accordingly, there is a need for an enhanced safety serial bus connector that is able to interface with standard cables or connectors.